Kinetics and Mechanism of Two-Electron Reduction of Surfacial Ferric Ions of Colloidal Ferrofluid byl-Ascorbic Acid in Aqueous Acidic Medium
✍ Scribed by Ram S. Shukla; Gadde Ramachandraiah; Rajendra P. Pant
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 63 KB
- Volume
- 210
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
The kinetics of electron transfer from L-ascorbic acid (H 2 A) to ferrofluid (FF) in dilute aqueous acidic solutions (pH 2.5-4.0) was investigated spectrophotometrically in detail as a function of [H 2 A], [FF], [H ؉ ], ionic strength, and temperature. FF was found to be reduced and the reduction was first-order dependent on both H 2 A and FF concentrations. An inverse first order dependence in H ؉ ion concentration and no dependence on ionic strength were observed. Kinetic, electrochemical, spectrophotometric, and thermodynamic results are interpreted in terms of a mechanism involving a rate-determining outer-sphere one-electron transfer from H 2 A to FF followed by a subsequent and kinetically rapid transfer of the second electron of H 2 A to the same molecule of FF, which was already reduced by one electron in rate-determining step. This overall two-electron transfer process from H 2 A to the same molecule of FF is discussed and compared with other closely related reactions.